Note: Descriptions are shown in the official language in which they were submitted.
- W O 95/09385 PCTrUS94/04903
~171~2
-
IMPROVED RELEASE AGENT SUPPLY WICK FOR
PRINTER APPARATUS AND METHOD FOR MAKING AND USING SAME
- BA~rr~'~UND OF THE INVENTION
1. Field of the Invention
The present invention relates to apparatus and method for
supplying a release coating to a fixing roller or similar device
such as those commonly found in printers and copiers.
2. Description of Related Art
A typical laser printer or plain paper copier contains a
series of rollers used to fix toner in place once it has been
transferred to paper. Generally the rollers comprise two rollers
in contact with one another and rotating in opposite directions--a
heated fixing roller and a resilient pressing roller. Once toner
has been transferred to a sheet of paper, the paper is passed
between the two rollers and toner is heat sealed in place.
In order to assure that the paper does not stick to the heated
fixing roller during this procedure, a wick containing a release
agent is mounted in contact with the roller along its length. A
2 0 traditional wick has usually comprised a fibrous strip, such as one
comprising NOMEX fiber sold by I. E. duPont de Nemours and Company,
Wilmington, DE. These felts can be acquired from conventional
industrial fabric suppliers such as Tex Tech Industries of North
Monmouth, Maine. The felt is presaturated with a release agent of
silicone oil (e.g. dimethyl polysiloxane). In addition to assuring
separation of the paper and fixing roller during the printing
process, the wick also serves as a wiper to clean contaminants,
such as residual paper dust, paper additives (e.g. clay, pigments)
and offset toner, from the hot fixing roller.
While traditional felt/oil wicks enjoy widespread use due in
part to their simplicity and relatively low cost, they are plagued
with a number of problems. First, oil impregnated felt tends to
provide inconsistent oil release, releasing excess quantities of
oil upon initial installation and steadily diminishing to
inadequate oil release over time. Second, felt tends to become
SUBSTITUTE SHEET
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`-- WO 95/09385 ;~ 1 71~ ~ 2 PCT/US94/04903
clogged and caked with toner residue. Residue build up leads to:
diminished ability of the felt to deliver oil; reduced
effectiveness at cleaning the roller; and increased friction and
wear upon the roller. Unfortunately, once contaminated, the matted
surface of the felt makes it impractical to clean and requires its
disposal. Third, the inability to clean the felt surface also
makes it infeasible to attempt to regenerate the wick for reuse,
leading to disposal problems and needless waste.
In recognition of some of these problems, a number of
modifications to the basic wick design have been proposed. As is
explained below, none is believed fully satisfactory.
In United States Patent 4,668,537 issued May 26, 1987, to
Matsuyama et al. it is proposed to adhere a strip of porous polymer
membrane to a felt wick. While this addresses some of the problems
inherent with use of a felt wick alone, there are a number of
anticipated impediments with this approach. First, proper adhesion
of a polymer membrane to a felt surface can be difficult to achieve
and delamination in use is a distinct risk. Second, like use of a
felt material alone, this device provides only a single contact
surface against the fixing roller, which may be subject to
premature wear and contamination. Third, the open nature of this
device limits the amount of oil which can be loaded into the wick
without leakage or clogging around the edge of the porous polymer
strip.
Some of these concerns are addressed in United States Patent
4,359,963 issued November 23, 1982, to Saito et al. This patent
teaches use of a elongated, relatively shallow bag of porous
polymer, such as polytetrafluoroethylene (PTFE), filled with heat-
resistant felt having silicone oil absorbed therein. Despite
improved containment of the oil within the felt, most embodiments
of this device continue to be problem prone, including: still
supplying only a single contact surface between the wick and the
fixing roller; requiring a somewhat difficult attachment of the
polymer bag to a mounting frame; and presenting a risk of
catastrophic oil leakage if the oil filled bag breaks. Another
embodiment taught in this patent proposes use of a rotating
polymer-covered felt wick. This approach may provide a better seal
of the liquid within the felt, but the rotating movement of the
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-- WO 95~1,9.385 ~ 1 7~ ~ 6 2 PCT/US94/04903
wick against the fixing roller is believed to be less effective at
cleaning the fixing roller surface and delivering oil onto the
roller surface.
United States Patent 4,375,201, issued March 1, 1983, to Kato,
employs a hollow tube of extruded porous PTFE which is filled with
silicone oil and sealed or covered at both ends to prevent leakage.
A coating of fluorocarbon rubber of other material is used to seal
the pores in the PTFE tube in those areas not in contact with the
fixing roller. While this applicator may address some of the
o problems of a felt and oil wick, as is discussed below it has a
number of other deficiencies.
First, the use of a hollow tube containing a free-f10wing
reservoir of oil is unacceptable in many instances. For instance,
the presence of a liquid reservoir means that the applicator must
be kept level in order to have an even distribution of oil across
the fixing roller. Additionally, the presence of oil in a free-
flowing form presents a risk of leakage and damage to the
equipment. To address the leakage problem, the patent teaches the
use of sealing mechanisms on either end of the tube; however, such
sealing mechanisms still present a risk of leakage and also add
unnecessary bulk to the apparatus. Finally, with the loss of oil
from the tube in the operation of the wick, undesirable distortion
or collapse of the tube is possible.
Second, without the stability of a firm mass of felt or other
material in contact with the roller, a hollow, tubular wick is
believed to be less efficient at cleaning the roller than
conventional felt-based wicks.
Third, the design of the apparatus of United States Patent
4,375,201 is believed to add little in the way of increased
operational life to the apparatus. Although the device appears
capable of refill, this procedure may be far too cumbersome and
prone to leakage for widespread acceptance. This conclusion is
bolstered by the patent's suggestion that the device may be
disposed of after use. Further, in order to avoid leakage, the
pores of the applicator are intentionally sealed around most of its
periphery to provide only a single roller contact surface. This
allows the applicator to be used only so long as this single
surface area can be maintained free from wear and residue build-up.
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Similar devices are disclosed in United States Patents
4,573,428 issued March 4, 1986, to Ogino et al. and 4,631,798
issued December 30, 1986, Ogino et al. Both of these devices
employ sealed porous polymer tubes filled with a free-flowing
liquid release agent. As such, each is believed to suffer from
deficiencies similar to those discussed above. Further, the use of
a polyethylene in United States Patent 4,573,428 is believed to
have a number of additional problems, such as uneven pore
structure, increased risk of clogged pores, and possible
lo contamination of heated fixing rollers.
A more complex wick apparatus is disclosed in United States
Patent 4,459,625 issued July 10, 1984, to Sakane et al. This
apparatus provides an open reservoir of release agent which can be
repeatedly refilled. Unfortunately, this applicator continues to
have only a single contact surface while being substantially
bulkier than any of the previously referenced devices.
Additionally, the use of free-flowing liquid also presents serious
leakage and operational limitations. Finally, this device requires
relatively complex assembly techniques in order to create an
adequate seal between the roller surface contact and the oil
reservoir.
Another problem which has emerged more recently centers around
the demand for small, portable high-quality printers and copiers.
The particular demands in storage and use inherent in the portable
market eliminates use of any release coating applicator which must
be maintained in a upright, much less level position.
Additionally, the size and weight demands for such equipment
requires that whatever device is used, it be as light, compact and
durable as possible.
Accordingly, it is a primary purpose of the present invention
to provide an apparatus for applying release chemicals to a roller
which is durable, delivers a consistent coating of chemical to the
roller, and provides effective cleaning of the roller.
It is a further purpose of the present invention to provide
such an apparatus which has improved operational life by being
readily adjusted to position multiple contact surfaces between
apparatus and the roller.
It is yet another purpose of the present invention to provide
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an apparatus for applying release chemicals to a roller which is
not prone to leakage and which can effectively operate at other
than level orientations.
It is still another purpose of the present invention to
5 provide an apparatus for applying release chemicals to a roller
which can be readily cleaned and reconditioned for reuse.
It is an additional purpose of the present invention to
provide straightforward methods to produce and use an applicator
with these properties.
These and other purposes of the present invention will become
evident from review of the following specification.
SUMMARY OF THE INVENTION
The present invention provides an improved applicator
apparatus for use in delivering release agent to fixing rollers or
15 similar devices in a variety of printers, including laser printers,
plain paper copiers and facsimile machines, etc.
The applicator apparatus of the present invention comprises:
an absorbent textile core, such as twisted fiberglass rope or cord,
filled with release agent; a permeable membrane, such as expanded
20 polytetrafluoroethylene, surrounding the textile core to form a
sheathed wick member; and a mounting sleeve for retaining the
sheathed wick member in contact with a fixing roller. Preferably,
the sheath wick member comprises an essentially cylindrical unit
open at each end which can be rotated to position different faces
25 in contact with the fixing roller.
In operation, the apparatus is mounted in contact with a
fixing roller in a conventional manner to provide a regular coating
of release agent to the fixing roller while continuously removing
excess toner and other contaminates from the roller. Once the
30 sheathed wick member has become loaded with contaminates or begins
to experience decrease oil delivery, it can be repositioned within
the mounting sleeve to present a different face in contact with the
fixing roller.
The applicator apparatus of the present invention provides a
35 far more constant and longer-lived coating of release agent than
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wo gs/0938s 2 1 7 1 8 6 ~ Pcr/usg 1,~ 1~03
has been previously available with conventional felt wick
applicators. Moreover, the applicator of the present invention can
be readily cleaned and regenerated for additional use once
expended. Finally, the applicator of the present invention is
s durable, requires minimal space, and can be stored, transported and
operated at different angles with minimal risk of spillage or
damage to printer.
DESCRIPTION OF THE DRAWINGS
The operation of the present invention should become apparent
from the following description when considered in conjunction with
the accompanying drawings, in which:
Figure 1 is a three-quarter isometric view of one embodiment
of a release agent applicator of the present invention shown
oriented with fixing and pressing rollers;
S Figure 2 is an enlarged, three-quarter exploded view of a
sheathed wick member of the present invention and a mounting
sheath, the sheath wick member shown with a portion of its porous
membrane surface cut-away;
Figure 3 is a graph illustrating release agent delivery verses
number of pages printed of a conventional felt and silicone oil
wick and a wick of the present invention;
Figure 4 is an enlarged, three quarter isometric view of
another embodiment of a spiral-wrapped sheathed wick member of the
present invention;
Figure 5 is a cross-sectional view of yet another embodiment
of a sheathed wick member and mounting sleeve of the present
invention;
Figure 6 is a cross-sectional view of still another embodiment
of a sheathed wick member and mounting sleeve of the present
invention;
Figure 7 is a graph depicting the rate of oil distribution
verses number of copies generated on a laser printer for two
different wick members of the present invention; and
Figure 8 is a graph depicting changes in wick member weight as
SUBSTITUTE SHEET
WO 95~5385 217 1 $ 6 ~ PCT/US9~ 19v3
a function of number of copies generated on a laser printer for two
different wick members of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an improved apparatus for use
in delivering a chemical agent to a roller. The apparatus of the
present invention is particularly applicable to the delivery of a
release agent such as silicone oil to a fixing roller of a laser
printer, plain paper copier or fax machine, or similar device. For
simplicity, such devices will be collectively referred to herein as
"printers."
As is shown in Figures 1 and 2, the release agent delivery
apparatus 10 of the present invention comprises a sheathed wick
member 12 and a mounting sleeve 14. As is shown in Figure 1, the
apparatus 10 is mounted to place the sheathed wick member 12 in
contact with a fixing roller 16 of a printer. The fixing roller 16
in turn is in direct contact with a resilient pressing roller 18.
As is known, once an image has been applied to a piece of paper,
the paper passes between the fixing roller 16 and the pressing
roller 18 to seal toner to the paper.
In order to prevent the paper from attaching itself to the
fixing roller 16, the release agent delivery apparatus 10 provides
a coating to the fixing roller 16 on each revolution of the roller.
Suitable release coatings for most applications include a silicone
oil, such as polydimethylsiloxane. The delivery apparatus 10 also
serves to wipe any excess toner or other residue or dust from the
fixing roller 16 to avoid contamination of future printer pages.
The sheathed wick member 12 of the present invention comprises
a permeable polymer membrane 20 completely surrounding an absorbent
textile core 22. The polymer membrane 20 should be sufficiently
porous to release agent that such release agent will pass readily
through it when it is compressed against a fixing roller 16 in
normal operation. Preferably the membrane 20 comprises a tube or
tape of fluoropolymer and especially a fluoropolymer of
polytetrafluoroethylene (PTFE). Permeable membranes of PTFE can be
derived through a number of processes, including by forming an
SUBSTITUTE SHEET
W O 95/09385 2 17 1 8 6 2 PCTrUS9~/04903
expanded network of polymeric nodes and fibrils in accordance with
the teachings of United States Patent 3,953,566 issued April 27,
1976, to Gore. This material is commercially available in a
variety of forms from W. L. Gore & Associates, Inc. of Elkton, MD,
under the trademark GORE-TEX.
Generally, a seamless tubular membrane should have the
following properties: a thickness of about 0.002 to 0.125 inches; a
porosity of about 30 to 98%; and a bubble point (with isopropyl
alcohol) of 0.4 to 60 psi. The preferred tubular membrane
properties are: a thickness of about 0.03 to 0.04 inches; porosity
of about 70 to 80%; and a bubble point of about 3-5 psi.
The Bubble Point of porous PTFE was measured using a method
similar to that set forth in ASTM Standard F316-86, with the
following modifications: isopropyl alcohol was used instead of
denatured alcohol; area tested was about 10 mm diameter (78.5 mm2).
The Bubble Point is the pressure of air required to blow the first
continuous bubbles detectable by the their rise through a layer of
isopropyl alcohol covering the PTFE media.
For a fluorinated ethylene propylene (FEP) coated tape
membrane, the membrane should have the following properties: a
thickness of about 0.0005 to 0.125 inches; and a porosity of about
30 to 98%. Preferably, a tape thickness is about 0.001 to 0.002
inches and a porosity of about 80 to 95%.
An expanded PTFE membrane is preferred for a variety of
reasons. First, the chemical inertness and relatively high heat
resistance of PTFE makes it completely suitable for use as part of
a wick in a printer environment. Second, expanded PTFE provides
even distribution of release agent. Additionally, the rate of
distribution of release agent can also be tightly controlled by
adjusting the dimensions and porosity of the expanded PTFE
membrane--assuring more uniform dissemination of release agent over
the operative life of the delivery apparatus. Third, expanded PTFE
has a low coefficient of friction and exceptional wear
characteristics, reducing wear on component parts and extending
operational life of the apparatus. Fourth, PTFE can be readily
cleaned of deposited toner and other contaminates, again extending
the operative life of the apparatus.
A preferred tape membrane for use with the present invention
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WO 9S1~9385 2 1 7 i ~ 6 rJ PCT/US9'1/04903
comprises an expanded PTFE material coated with a thermoplastic
polymer with a melting temperature below that of the expanded PTFE.
The thermoplastic layer should be 1/2 to 1/10 or less of the
thickness of the PTFE material. The PTFE and thermoplastic
polymer composite is heated to a temperature sufficient to soften
or melt the thermoplastic polymer into the expanded PTFE surface
but below that which will melt the PTFE (i.e. below about 342C).
Thermoplastic polymers are preferred since they are similar in
nature to PTFE (i.e. they have melt points near the lowest
crystalline melt point of PTFE, and they are relatively inert in
nature and therefore resist chemical attack). Suitable
thermoplastic polymers for use with the present invention may
include: fluorinated ethylene propylene (FEP), copolymer of
tetrafluoroethlene and perfluoro(propylvinyl ether)(PFA),
homopolymers of polychlorotrifluoroethylene (PCTFE) and its
copolymers with tetrafluoroethylene (TFE) or vinylidene fluoride,
ethylenechlorotrifluoroethylene (ECTFE) copolymer, ethylene-
tetrafluroethylene (ETFE) copolymer, polyvinylidene fluoride
(PVDFG), and polyvinylfluoride (PVF).
The preferred material for use as a tape in the present
invention is a composite fluoropolymer film/membrane comprising a
noncontinuous thermoplastic fluoropolymer layer (more preferably a
non-continuous layer of fluorinated ethylenepropylene (FEP)) and an
expanded PTFE layer.
The porous membrane is laid on the core 22 with the
thermoplastic layer facing the core 22. Wrapping the wick with the
porous membrane may be done by hand either spirally or in a
"cigarette" fashion. Wrapping is preferably accomplished using a
spiral tape wrap machine such as those known in the art of wrapping
dielectric layers around conductors. One such machine is taught in
United States Patent 3,756,004 to Gore. The tape wrap machine
applies the porous membrane with back tension in a helical fashion
around the PTFE core. Back tension allows oil from the core to
wet-out the tape rapidly.
The resulting composite material is heated to a temperature
above the melt point of the thermoplastic fluoropolymer layer and
at or below about 350C so that the contacting layers of the
membrane adhere. The material should be kept under tension when
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heated. Heating can be done through any common method, including
use of conduction or convection heat.
Housed within the membrane 20 is an absorbent textile core 22
which is filled with release agent. The textile core 22 may be a
twisted or braided rope of fibrous strands which will provide a
substantial reservoir of release agent. Additionally, the textile
core 22 should be sufficiently resilient to deformation so as to
provide support to the membrane 20 when it is placed in contact
with roller 16. Other possibly suitable textile materials include
0 cords, yarns, tow, sliver, fabric, or felt. These may be
constructed from materials such as fiberglass, aramids,
s copolyimides, polyimides, fluoropolymers (e.g.
chlorotrifluoroethylene (CTFE) or polytetrafluoroethylene (PTFE)),
polyphenylene sulfide (PPS), modacrylic, novoloid, polyester,
acrylic, or similar materials or combinations or blends of such
materials. Additionally, the textile core may comprise an open
cell foam, such as silicone, urethane, melamine, fluoropolymer, and
mixtures thereof. The primary concern is to select a material
which is suitable for use in a printer environment (e.g. being
resistant to attack by the release agent; being able to handle
operating temperatures of the fixing roller; etc.).
The membrane 20 illustrated in Figure 2 comprises a continuous
tube of expanded PTFE placed around textile core 22. This
construction may be achieved by any conventional means, including
by extruding membrane 20 around the textile core 22 or by pulling
the textile core 22 into the membrane 20. The textile core 22 may
be filled with the release agent prior to insertion into the
membrane 20, or it may be filled after insertion by injection under
pressure or vacuum or by merely soaking the sheathed wick member 12
within a release agent material.
It has been found that the textile core 22 provides a
sufficiently absorbent substrate so that the release agent will
remain therein without conscientious sealing of the membrane 20
around the textile core 22. As such, each end 24, 26 of the
sheathed wick member 12 may be left open. Although not necessarily
required, this open construction provides a number of benefits,
including giving easy access for replenishing release agent;
limiting the size of the sheathed wick member 12 to only its
SU{3STITUTE SHEET
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WO 95~65 PCT/US~q/O 1303
11
operational length--eliminating additional space which might be
required for end caps or other sealing means; reducing labor and
material costs for construction; etc. An additional benefit is
that open ends allow the unit to pressure equalize (i.e.. to
function properly, sealed units should include added means to
achieve pressure equalization, or else the flow of oil from the
unit will steadily decrease due to vacuum formation within the
unit).
The delivery apparatus 10 may be mounted in contact with the
fixing roller 16 in any suitable manner. As is known, most printer
devices include clips or brackets adapted to receive a wick and
retain it in contact with the fixing roller 16. It should be
evident from the above description that the mounting sleeve 14 of
the present invention can be readily provided with appropriate
hardware to interface with such mounting systems.
Shown in Figure 3 is a hypothetical graph depicting the
relative delivery of release agent per page over a number of pages
for a conventional felt/oil wick 25 and a sheathed wick member 27
of the present invention. As can be seen by this graph, a
conventional wick tends to provide far too much oil upon immediate
installation and then falls off rapidly to provide too little oil.
By contrast, a wick of the present invention provides a more
consistent oil coating to the fixing roller over its operational
life, and, as a result, should tend to have an extended duty cycle,
and provide better image quality.
Another embodiment of a sheathed wick member 28 of the present
invention is shown in Figure 4. In this form, the wick member 28
is formed by spiral wrapping a porous membrane 30 around a textile
core 32 in the manner described above.
A composite tape of expanded PTFE membrane and FEP tape with
the following properties is preferred. The tape is ideally a
porous, non-continuous FEP coated expanded PTFE tape which has been
highly expanded in the machine direction about 80:1 or more. The
high degree of expansion imparts high strength to the material in
the direction of expansion. Overall dimensions of the tape is
preferably about 1 inch wide and 0.001 to 0.005 inch thick. The
tape is applied to the core with an overlap of about 1/2 (i.e.
covering the core about two times).
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-- WO 9~ 385 PCT/US9~ 19v3
12
The textile core 32 in the embodiment of Figure 4 comprises a
0.0374 inch diameter matrix braid fiberglass rope with a base
weight of about 30 grams/foot. The rope is impregnated with
silicone oil (e.g. DOW 200 fluid).
Other examples of possible embodiments of the sheathed wick
members of the present invention are illustrated in Figures 5 and
6. The embodiment of Figure 5 demonstrates that the sheathed wick
member 34 can be formed in an essentially rectangular shape. This
form has a number of advantages in that it provides an extended
contact surface 36a against which to contact a fixing roller 16.
With the use of a resilient textile core material 38, such as
needle punched felts, tow fiber, or open cell foams, the contact
surface would be expected to conform somewhat to the shape of the
fixing roller for improved cleaning and release agent application.
As should be evident, the sheathed wick member 34 may be readily
removed and reinserted to provide up to four fresh contact surfaces
36a, 36b, 36c, 36d before the wick member must be cleaned or
replaced.
The embodiment shown in Figure 6 is yet another example of a
sheathed wick member 40. In this form, the sheathed wick member 40
comprises an essentially triangular shape which is retained in
place by contoured mounting sleeve 42. Preferably, the wick member
40 is mounted against the fixing roller 16 to place its pointed
ends 44a, 44b, 44c in contact with the fixing roller 16. Again,
the textile core 46 material should comprise a deformable material,
such as a needle punched felt or an open cell foam, to improve
surface contact area.
It should be evident from these examples that a wide variety
of other shapes may likewise be provided for the sheathed wick
member and mounting sleeve of the present invention without
departing from its intent.
One of the advantages of the apparatus 10 of the present
invention is that it can be cleaned and regenerated for further
use. The preferred cleaning and regenerating steps comprises
wiping the collected residue from the surface of the wick using an
absorbent cloth. The core is then re-injected with silicone oil,
either manually with a syringe or automatically with a pressurized
oil delivery syringe system.
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A simplified procedure for regenerating the wick comprises simply
rotating the sheath and core approximately 90 degrees and then, if necessary,
re-injecting with silicone oil as described above.
Without intending to limit the present invention, the following represent
5 examples of sheathed wick members which were made and used in
accordance with the present invention:
EXAMPLE 1
An expanded porous polytetrafluoroethylene tubing with an outer
diameter of about 9 mm and an inner diameter of about 7 mm was used to
make fuser oil application wicks for a laser printer. Each tube was filled with a
core of various material and filled with a DOW CORNING 200 silicone oil
acquired from Dow Corning Corp. of Midland, Michigan.
Samples were prepared in the following manner:
For a core of polyester felt (poly felt), 2720 g/m2 (65Oz/yd2) by 9.5 mm
(3/8") thick polyester felt was cut into 9 5 mm x 6.4 mm x 28 cm (3/8" x 3/8" x
11") strips. These strips were weighed and evenly coated with 12 grams of
DOW CORNING 200 silicone oil fluid (10,000 centistoke). The oiled strips
were placed horizontally on a glass dish so that the oil could evenly distributethroughout the polyester felt. The oiled felt was then pulled through a 38 cm
(15") long expanded PTFE tube. Pulling through the tube was accomplished by
attaching a safety pin to the felt and tying a metal wire to the safety pin and
passing the wire through the tube. . Once the expanded PTFE tube was pulled
over the oiled felt, both the tube and the felt were cut to 21.6 cm (8.5") in length
and weighed.
Wicks prepared in accordance with the above procedures were then
tested with various weights and viscosities of silicone oils in a drip test. Each
sample was clamped in a ring-stand and hung vertically for a period of days. A
paper towel was placed below the hanging sample to catch any oil that flowed
out. Drips of oil that were observed on the paper towel were noted. Wicks
"passed" the drip test when absolutely no drips were observed after ten (10)
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days. No dripping is desirable to ensure that the proper amount of
oil is transferred during the operation of the copier. Drip tests
were conducted by varying the material, oil weight, and oil
viscosity. The following results were observed:
WICK DRIP DATA
Oil Viscosity
Sample No. Material Oil Wt. (q) (Centistokes)
1 Fiberglass rope 12.0 30,000
2 Polyester felt 12.2 30,000
lo 3 NOMEX felt 12.3 30,000
4 Poly felt 12.7 10,000
Poly felt 6.3 10,000
6 NOMEX felt 12.1 10,000
7 NOMEX felt 6.5 10,000
8 Fiberglass rope 6.3 10,000
9 Fiberglass rope 12.1 10,000
MELAMINE foam 6.0 30,000
Each of the materials of Samples Nos. 1 through 9 were installed
within-expanded PTFE tubes in the manner described above. After
ten days, no oil drips were observed from any of Samples Nos. 1
through 8. Sample 9 did experience dripping after ten days and is
considered to have "failed" the drip test. Sample 10 also failed
the drip test, with dripping beginning after only 24 hours.
To test the wick's functionality, pre-weighed wicks similar in
construction to that of Sample 2 and 4 above were inserted into a
QMS PS820 laser printer. A total of 8,600 copies were generated
with these wicks in place. After various numbers of intermittent
copies were run, including as few as 20 copies and as many as 900
copies, the wicks were removed from the printer and re-weighed. By
taking difference in the weights before and after the copies were
run, the intermittent and total oil transfer rates were calculated.
Graphs of wick weight verse number of copies and of oil delivery
rate verses number of copies were produced in order to quantity the
SUBSTITUTE SHEET
W095/0938S ~1718 6 2 PCT/US~/01~03
oil transfer as a function of the printer runs. These results are
plotted as lines 48 and 52 on the graph of Figures 7. The weight
loss of the wick as a function of the number of copies printed is
shown as lines 50 and 54 on the graph of Figure 8. Transfer rates
5 were considered somewhat higher than desired.
EXAMPLE 2
A polyester felt of 2720 g/cm2 basis weight with a thickness
of 9.5 mm was again cut into 9.5 mm x 6.4 mm x 12.7 cm strips. The
strips were pulled through ePTFE tubbing using the safety pin and
metal wire procedure previously described. Once the felt was
installed in the tubing, the felt was oiled using 12.04 9 of DOW
CORNING 200 fluid 30,000 centistoke silicone oil. Oil was injected
at both ends using a 12.7 cm (5") long needle and syringe. The
oiled sample was then placed horizontally on-a glass dish to allow
15 the oil to flow evenly through the sample. The oiled sample was
then cut to 21.6 cm (8.5") in length and was weighed.
After passing the drip test, the oiled wick was again placed
in a QMS PS820 laser printer, and an total of 7,100 copies were
generated, After every 500 copies, the wick was removed and re-
20 weighed in order to calculate the total and intermittent oiltransfer rates. This trial resulted in an oil transfer rate
significantly lower than that achieved in Example 1. The oil
transfer rate was considered acceptable for use in a printer
device.
While particular embodiments of the present invention have
been illustrated and described herein, the present invention should
not be limited to such illustrations and descriptions. It should
be apparent that changes and modifications may be incorporated and
embodied as part of the present invention within the scope of the
following claims.
SUE~STITUTE SHEET
